期刊名称：ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences
印刷版ISSN：2194-9042
电子版ISSN：2194-9050
出版年度：2010
卷号：XXXVIII - Part 8
页码：1042-1045
出版社：Copernicus Publications
摘要：Due to the global warming issue, the trend analysis of sea ice area is becoming quite important. P assive microwave sensors on board satellites can monitor the global distribution of sea ice on daily basis. In extracting sea ice concentrations from passive microwave sensors onboard satellites, atmospheric effects mainly caused by the presence of atmospheric water vapor, cloud liquid water, rain and sea surface roughening by winds are likely to estimate certain sea ice concentrations at the open water area. We call this kind of area as "false sea ice area". To solve the problem, usually, weather filters are applied. The basic idea of weather filters is to differentiate clouds over open water from sea ice in the characteristic domain derived from brightness temperatures, and reject clouds by using thresholds . However, it is known that sometimes clouds over open water and sea ice are overlapped in the characteristic domain. So, sea ice concentrations less than 15% are often rejected when counting sea ice extent or sea ice area from sea ice concentration data derived from passive microwave sensors data. Here we call this as 15% rejection method. But, it is also known that sometimes more than 15% sea ice concentrations are calculated when open water are covered with heavy clouds etc. Moreover, 15% rejection method also rejects true low concentration sea ice. In this study, authors have applied three days minimum method for reducing the false sea ice area. The algorithm is to take the minimum sea ice concentration value within the three days observation as output of each pixel. The basic idea of the algorithm is that heavy clouds may not stay in one place for more than three days, and sea ice may be more stable than heavy clouds. The result showed that the proposed method can effectively reduce the false sea ice area than 15% rejection method. Moreover, when calculating sea ice extent, the proposed method could calculate more than 15% rejection method. This suggests the effectiveness of the new method for reducing the cloud effect for calculation sea ice extent
关键词：Sea of Okhotsk; HDV; thin sea ice; Monbetsu Bay
